This is a discussion on The 100% CORRECT, Multi-picture, Non-ghetto, STI I/C sprayer installation within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; This spot is reserved for an all-inclusive Youtube video (to be filmed shortly) detailing all aspects, functions, parameters, and metered ...

This spot is reserved for an all-inclusive Youtube video (to be filmed shortly) detailing all aspects, functions, parameters, and metered performance advantages of a full STI intercooler sprayer system transplanted into a 2006 WRX.

Please continue reading the below picture thread to see a detailed description of the complete (and correct) installation.

EDIT - 11 Jan, 2011: With as cold as it is outside (10-15 degrees), the I/C spayer has virtually no effect on the intake temp, as it is already, literally freezing. I will still do a video. My plan is to do a 50-80mph 5th gear pull and time it.... then do a 2nd pull after the I'c has been sprayed, while using my pre and post I/C intake temp gauges as a guide. Should be a good video, but it will have to wait until it gets warmer.

I have been collecting parts and doing research on this for nearly 2 months. You would be absolutely AMAZED to discover how much bad, or incorrect information there is out there. I’ve found that most pictoral threads detailing I/C sprayer systems are either:

I’ve found that there is almost ZERO information on how to do an actual transplant of a 100% factory STI I/C sprayer system into a WRX… the RIGHT way. Not jimmy-rigged, not ghetto, with all correct parts, installed correctly, and functioning properly. Again… I researched EVERYTHING out there, and over 90% of it is completely wrong, or not worth doing.
So, before I begin, I thought I’d go ahead and clear up several misconceptions I managed to discover, usually the hard way.

1. The intercooler sprayer SWITCH should NOT be grounded. (trust me, it’s correct)
2. You need the STI spray timer relay to get the 2-3 second burst
3. Running pump power through the switch by “holding” the switch down will burn out the internal light
4. The Subaru schematics ARE correct, but they are MIRROR images of how the plugs actually look.

First things first, lets start with all the parts I used:

4-way wire:

LEDs (I’ll explain why in the instructions)

STI I/C switch:

Side view:

The switch prongs:

STI trunk carpet

STI I/C sprayer tank and pump:

Sprayer tank prongs

Various electrical supplies

STI spray timer relay (Subaru part # 88017FE040)

Relay prongs:

3/16 “L” tubes

Special female wire terminals (NAPA part # 725273)… be warned, they are $1.40 a piece. You need 9 of them, but you should get several extra

STI sprayer nozzle (Subaru part # 86636FA120)

3/16 ID tubing – 20 ft

STI sprayer check valve (Subaru part # 86634AG010)

Standard size insulated female wire terminals

A few other items were required that I had on hand – standard stuff, vampire clips, electrical tape, and LOTS of zip ties, etc.

Now…. Onto the installation. First off, I had several goals that I wanted to achieve in addition to just having a sprayer system:

1. I wanted it to function EXACTLY like the factory STI system
2. I wanted the tank low-level indicator to work, as the WRX gauge cluster does not have the low-level indicator (amber LED)
3. I wanted to have a “pump activation light” (green LED) for troubleshooting purposes, as well as to know when the pump has finished cycling, so I can press it again if need be. Pressing the button twice does not make it pump longer, you have to wait for it to finish cycling before you can spray again.
4. I wanted the switch to be close to the shifter, so my left hand never has to come off the steering wheel. The factory STI system switch is located to the left of the steering wheel, and requires you to take your right hand off the shifter to hold the wheel, and then take your left hand off the wheel to activate the switch…. And then return back to your normal driving position every time you want to spray. This is a poor design in my opinion, so I thought I’d fix it.

First things first… disconnect the battery

Passenger seat, rear seat, and door sills must come off

Interior trunk carpet removed

Remove the driver side lower dash to access the foglight wiring and fuse box. You need to vampire clip the following wires from the foglight harness (foglight harness is installed in ALL cars, regardless of whether or not foglights are installed (I don’t have foglights)
Red, Violet, Orange with white stripe, and black (I used a different ground from other electrical work, but you will need to find a black groundwire)

Above the fusebox, you’ll also find the yellow wire with the red stripe. Use heavier gauge wire when you vampire clip into this wire.

Using zip ties, route the wires down the center console and bring them up through these holes

Now, do the exact same thing through the other hole, under the passenger side carpet (4 wires, plus one large gauge wire (10 or 12)….. and then run all 5 wires down the side of the car, under the carpet, by the brake lines. Use lots of zip ties

Run them into the trunk. I found a nice place, just inboard from the RR strut tower. Just ziptie your wires to the factory harness.

This is what it looks like from inside the trunk

Back inside the car, your wires should be coming from both directions. You’ll install the switch to make the connection

Now you’ll need to run your tubing. I found this firewall grommet on the passenger side of the engine bay. One tiny slit with a razor, and it slid right through.

You’ll need to drop down the passenger side lower dash, and the glovebox. You can see where the tubing comes through

Install the check valve, route it through the hood to secure it, and use the “L” tubes to cleanly route the tubing up to the sprayer nozzle

Now route your tubing under the carpet, right along side the wiring

Route your tubing and wiring to the back of the car where the pump is. I took this picture with the trunk OPEN…. Make sure you route it OVER the trunk hinges, or you will likely destroy your work.

I took this picture with the trunk CLOSED. See what would have happened if we routed the wire below the trunk hinges?

Here’s what the inside of the trunk looked like after I wired everything up and ziptied everything

I had to fab up this bracket to secure the front of the tank (GHETTO!!!!)…. I didn’t know I required this part, but I’m on the hunt for the correct part now.

Trunk completed

Interior completed
When the level of water in the tank is low:

While the pump is activated (stays on 2-3 seconds only while pump is pumping)

I spent 2 full days figuring this out…. Sifting through so much internet garbage… only to discover it was done the wrong way. I did manage to get bits and pieces of correct information, but it was few and far between, and coupled with additional incorrect information. It made it extremely difficult to decipher what was right, and what was wrong.
Here’s the factory Subaru wiring diagram in an STI. It is correct, but it is “backwards” from how you actually view all the terminals. If you keep that in mind, you’ll be fine. Subaru views the terminals as if you were looking at them from the “backside”, but in actuality, when installing them, you see them from the front.

However…. This is a FACTORY STI wiring diagram…. So it’s not really meant to be used as a “transplant”. Plus, it doesn’t include the extra indicator lights I added. So…. I created this wiring schematic… based upon the actual pictures I took. Hopefully it helps, and it’s easy to read.

Now I have a nice shopping list for my Christmas money. Although I'm not sure where I'll be able to dig up the trunk liner. Look around for a parts car I suppose? Perhaps I could relocate the tank into the fender where my intake silencer used to be. There's lot of space in there now, just need to extend the filler hole into the engine bay...

Milennium auto parts.... they will sell you a trunk liner (carpet), switch, tank, and pump for about $150. That is the MOST you should ever pay for it. They do NOT include the relay though.... which in my opinion, is a necessity. I don't want to have to "hold" the button down to spray, while I'm trying to focus on the track.

check ebay... local sales, etc

I bought the tank, pump, and carpet from a local guy for $70

The switch was $20 on ebay

The relay is OFTEN skipped, because it is expensive, and no one sells it used. Not to mention, there is a HUGE lack of information out there about it. Most people don't even know it exists. From Subaruparts.com it was about $60 shipped.

The wire terminals were the toughest to find.... and CRAZY expensive for what you get... unfortunately they are a necessity. The guys at NAPA freaked out when they saw the price of them ($1.40 a piece). They ended up hooking me up, and selling them to me under a dealer account for $1.00 a piece.

Check valve was $6.00 from Subaru

Sprayer nozzle was like $12.00 from Subaru.

everything else.... was just extemporaneous supplies.... maybe another $25 or so??

A year and a half later, and you're saving me in more ways that you think XD I will be bookmarking this, and it'll be my biggest reference for my install! I'll be installing it in the stock position, and I'll run the lights through the blank space next to it where the headlight angle adjustment would be. Thanks for the awesome write up, now I know what else I need!!

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